AgBiS2 quantum dot solar cell and preparation method thereof
Patent Information
- Application Number
- CN202611075631.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-20
- Publication Date
- 2026-08-21
AI Technical Summary
然而，这种方法增加了工艺步骤，且修饰层与SnO2之间的结合力可能不足，长期稳定性存在隐患
[0021]有益效果：本发明与现有技术相比，取得如下显著效果：（1）通过将卤素化合物直接添加到SnO2电子传输层前驱体溶液中，实现卤素离子的原位掺杂与缺陷钝化，从而显著提升界面质量和器件的光电转换效率。（2）与现有技术中在SnO2层与量子点层之间引入独立修饰层的方法不同，一方面本发明在成膜前实现卤素离子的原位掺杂与缺陷钝化：卤素离子填补SnO2表面的氧空位，阳离子与表面羟基作用，大幅降低界面陷阱态密度；同时形成界面偶极层，优化能级匹配；另一方面本发明采用混合掺杂的方式，卤素化合物均匀分布于整个SnO2层中，不仅简化了工艺步骤，而且修饰效果更加稳定、持久。（3）本发明与现有电池制备流程完全兼容，无需额外增加独立修饰层步骤。（4）采用本发明方法制备的AgBiS2量子点太阳能电池，开路电压提升至0.52以上，填充因子提升至0.7以上，光电转换效率显著提高。
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Figure CN122622480A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a solar cell and its preparation method, and more particularly to an AgBiS2 quantum dot solar cell and its preparation method. Background Technology
[0002] Silver bismuth sulfide (AgBiS2) quantum dots have shown significant potential in novel thin-film solar cells due to their high absorption coefficient, environmentally friendly composition, and solution-processability. Typical AgBiS2 quantum dot solar cells usually employ tin oxide (SnO2) as the electron transport layer to achieve efficient electron extraction and hole blocking. However, in existing devices, the open-circuit voltage (V... OC The photoelectric conversion efficiency (PCE) and fill factor (FF) are still significantly lower than theoretical expectations, limiting further improvements in photoelectric conversion efficiency.
[0003] Analysis shows that the interfacial defect states and energy level mismatch between the SnO2 electron transport layer and the AgBiS2 quantum dot absorption layer are the main factors leading to severe nonradiative recombination and low open-circuit voltage and fill factor. Numerous defects, such as oxygen vacancies, exist on the SnO2 surface, which act as electron traps, exacerbating interfacial recombination. Furthermore, the significant conduction band shift between SnO2 and AgBiS2 hinders efficient electron transport.
[0004] In existing technologies, a common approach to improve the interface is to introduce an independent modification layer (such as an organic small molecule or a self-assembled monolayer) between the SnO2 layer and the quantum dot layer. However, this method increases the number of processing steps, and the bonding force between the modification layer and SnO2 may be insufficient, posing a risk to long-term stability. Summary of the Invention
[0005] Purpose of the invention: The purpose of this invention is to provide an AgBiS2 quantum dot solar cell that can be directly modified inside SnO2 without the need for introducing an additional independent layer; the second purpose of this invention is to provide a method for preparing the above-mentioned AgBiS2 quantum dot solar cell.
[0006] Technical solution: The AgBiS2 quantum dot solar cell of the present invention includes a transparent electrode, an electron transport layer, an absorption layer, a hole transport layer and a metal electrode. The electron transport layer is a tin oxide thin film doped with a halogen compound. The halogen compound and the tin oxide precursor are mixed before film formation to form a uniform doped electron transport layer.
[0007] The halogen compound is selected from at least one of organic halogen salts, inorganic halogen salts, or halogen ionic liquids.
[0008] The halogen compound is selected from at least one of methylammonium bromide, methylammonium chloride, methylammonium iodide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, phenylethylammonium bromide, phenylethylammonium chloride, and phenylethylammonium iodide.
[0009] The thickness of the doped tin oxide film is 20–50 nm.
[0010] The transparent electrode is indium tin oxide (ITO) or fluorine-doped tin oxide (FTO); the absorption layer is preferably an AgBiS2 quantum dot absorption layer with a thickness of 20–100 nm; the hole transport layer is a bilayer structure, including a main hole transport layer and a hole injection buffer layer. The main hole transport layer is selected from poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) or poly(3-hexylthiophene) (P3HT) with a thickness of 10–30 nm; the hole injection buffer layer is MoO3 with a thickness of 2–5 nm. The bilayer structure can effectively match the energy levels of the AgBiS2 quantum dot absorption layer and improve hole extraction efficiency; the metal electrode is a silver electrode.
[0011] The above-mentioned method for preparing AgBiS2 quantum dot solar cells includes the following steps:
[0012] (1) The halogen compound is mixed with the tin oxide precursor solution, spin-coated or sprayed onto the surface of the transparent electrode, and then annealed to form a dense tin oxide film doped with the halogen compound.
[0013] (2) Deposit an AgBiS2 quantum dot absorption layer on the doped tin oxide film;
[0014] (3) A hole transport layer and a metal electrode are sequentially prepared on the AgBiS2 quantum dot absorption layer to obtain the solar cell.
[0015] In step (1), the annealing temperature is 150-300 ℃ and the annealing time is 5-60 min.
[0016] In step (1), the concentration of the halogen compound in the tin oxide precursor solution is 1 to 15 mg / mL.
[0017] In step (1), the molar ratio of the halogen compound to the tin oxide precursor is 0.01:1 to 0.5:1.
[0018] In step (1), the spin coating time is 30 to 60 seconds.
[0019] In step (2), the AgBiS2 quantum dot absorption layer is prepared by a layer-by-layer spin coating combined with a solid-phase ligand exchange process. The solution used for ligand exchange is a 3-mercaptopropionic acid / hexafluoroisopropanol solution with a mass-volume ratio of 0.5-5%.
[0020] Invention Principle: The core of this invention lies in improving the interfacial properties of the SnO2 electron transport layer by using mixed doping of halogen compounds and SnO2 precursors. The key to the AgBiS2 quantum dot solar cell structure of this invention is that there is no independent modification layer between the SnO2 electron transport layer and the absorption layer; instead, it is a doped SnO2 thin film obtained by in-situ halogen doping of SnO2 within the SnO2 electron transport layer to achieve interfacial modification. Specifically, the halogen ions in halogen compounds, such as methylammonium bromide (MABr), methylammonium chloride (MACl), methylammonium iodide (MAI), tetrabutylammonium bromide (TBABr), tetrabutylammonium chloride (TBACl), tetrabutylammonium iodide (TBAI), phenylethylammonium bromide (PEABr), phenylethylammonium chloride (PEACl), and phenylethylammonium iodide (PEAI), i.e., Br... - Cl - I - It can fill oxygen vacancies on the SnO2 surface, and cations such as MA can fill these vacancies. + TBA + TMA + It can interact with hydroxyl and other groups on the SnO2 surface, thereby significantly reducing the density of interfacial trapped states and suppressing nonradiative recombination. Simultaneously, the introduction of halogen compounds can modulate the Sn content in SnO2. 2+ / Sn 4+ The proportion of SnO2 was optimized to improve its energy level matching with AgBiS2 quantum dots. Furthermore, the halogen compound formed an interfacial dipole layer on the SnO2 surface, increasing the built-in electric field and facilitating electron extraction. In the in-situ halogen passivation process, the proportion of Sn in SnO2 was adjusted. 2+ / Sn 4+ Optimizing the conduction band position of SnO2 by adjusting the ratio depends on the doping concentration of the halogen compound. Appropriate halogen ions can fill oxygen vacancies, inducing SnO2 conduction band position through charge compensation. 2+ Oxidized to Sn 4+ , making Sn 2+ / Sn 4+ The ratio has changed. Simultaneously, the organic cations form a surface dipole layer, further stabilizing Sn. 4+ Crystal lattice.
[0021] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects: (1) By directly adding halogen compounds to the SnO2 electron transport layer precursor solution, in-situ doping and defect passivation of halogen ions are realized, thereby significantly improving the interface quality and the photoelectric conversion efficiency of the device. (2) Unlike the method of introducing an independent modification layer between the SnO2 layer and the quantum dot layer in the prior art, the present invention realizes in-situ doping and defect passivation of halogen ions before film formation: halogen ions fill the oxygen vacancies on the SnO2 surface, and cations interact with surface hydroxyl groups, greatly reducing the interface trap state density; at the same time, an interface dipole layer is formed to optimize energy level matching; on the other hand, the present invention adopts a mixed doping method, and the halogen compounds are uniformly distributed in the entire SnO2 layer, which not only simplifies the process steps, but also makes the modification effect more stable and durable. (3) The present invention is fully compatible with the existing battery preparation process and does not require additional independent modification layer steps. (4) The AgBiS2 quantum dot solar cell prepared by the method of the present invention has an open-circuit voltage of more than 0.52, a fill factor of more than 0.7, and a photoelectric conversion efficiency that is significantly improved. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of an AgBiS2 quantum dot solar cell according to an embodiment of the present invention;
[0023] Figure 2 The JV characteristic curves of AgBiS2 quantum dot solar cells obtained by adding MABr, MACl, and MAI to Examples 1 to 3 of the present invention are compared.
[0024] Figure 3 This is a comparison of the JV characteristic curves of AgBiS2 quantum dot solar cells obtained by adding different concentrations of MABr in Example 2 and Comparative Examples 3 to 5 of the present invention.
[0025] Figure 4 This is a comparison of the JV characteristic curves of AgBiS2 quantum dot solar cells obtained at different annealing temperatures in Example 2 of the present invention and Comparative Examples 6 to 8.
[0026] Figure 5 This is a comparison of the ultraviolet absorption of SnO2 films with different concentrations of MABr added in Example 2 and Comparative Examples 3 to 5 of the present invention.
[0027] Figure 6 This is an XRD comparison diagram of the doped SnO2 film of Example 2 of the present invention and the pure SnO2 film of Comparative Example 3. Detailed Implementation
[0028] The present invention will now be described in further detail.
[0029] Example 1
[0030] This embodiment provides an AgBiS2 quantum dot solar cell containing MABr-doped tin oxide, the structure of which is as follows: Figure 1 As shown, from bottom to top, it includes a transparent glass 1, an indium tin oxide transparent conductive film (hereinafter referred to as ITO) 2, an MABr-doped SnO2 electron transport layer 3, an AgBiS2 quantum dot absorption layer 4, a hole transport layer 5, and a metal electrode 6. The transparent electrode includes the transparent glass 1 and ITO 2, hereinafter referred to as ITO conductive glass; the hole transport layer 5 is the main hole transport layer poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and the hole injection buffer layer MoO3; and the metal electrode 6 is silver.
[0031] The battery is prepared as follows:
[0032] (1) The ITO conductive glass was ultrasonically cleaned with deionized water and ethanol for 20 min each, dried with nitrogen, and then treated in an ultraviolet ozone cleaner for 3 min. Preparation of MABr / SnO2 mixed solution: 12 mg of MABr was weighed, 1 mL of SnO2 colloidal stock solution with a mass fraction of 12 wt% was added, and 2 mL of deionized water was added for dilution. Then, it was ultrasonically dispersed for 15 min to obtain a mixed solution with a MABr concentration of about 4 mg / mL. The mixed solution was spin-coated onto the ITO substrate at a speed of 3000 rpm for 45 s, and annealed in air at 270 ℃ for 15 min to form a MABr-doped SnO2 electron transport layer with a thickness of about 30 nm.
[0033] (2) AgBiS2 quantum dots were synthesized using the existing hot-injection method and dispersed in toluene to form a 20 mg / mL AgBiS2 quantum dot solution. The 20 mg / mL AgBiS2 quantum dot solution was then spin-coated onto the surface of an MABr-doped SnO2 electron transport layer. Subsequently, a 1% (v / v) solution of 3-mercaptopropionic acid / hexafluoroisopropanol was added for ligand exchange, which replaced the long-chain ligands on the AgBiS2 quantum dot surface with short-chain ligands, thereby enhancing interlayer charge transport. The spin-coating-exchange steps were repeated until an AgBiS2 quantum dot absorption layer with a thickness of approximately 60 nm was deposited on the MABr-doped SnO2 electron transport layer.
[0034] (3) Dissolve 2 mg PTAA in 1 mL toluene to obtain a PTAA solution with a concentration of 2 mg / mL. Spin-coat the PTAA solution onto the AgBiS2 quantum dot absorption layer to obtain a PTAA master hole transport layer with a thickness of 5 nm.
[0035] (4) A 3 nm thick MoO3 hole injection buffer layer was deposited on the surface of the PTAA main hole transport layer by thermal evaporation.
[0036] (5) Finally, a 120 nm thick silver anode was deposited on the surface of the MoO3 hole injection buffer layer by thermal evaporation to obtain the following: Figure 1 The structure shown.
[0037] Example 2
[0038] The only difference between this embodiment and Example 1 is that in step (1), the amount of MABr added is 20 mg, and the concentration of MABr in the resulting mixed solution is about 6.7 mg / mL.
[0039] Comparative Example 1
[0040] The only difference between this comparative example and Example 1 is that in step (1), MABr is replaced with an equimolar amount of methyl ammonium chloride (MACl), and the concentration of MACl is 2.41 mg / mL.
[0041] Comparative Example 2
[0042] The only difference between this comparative example and Example 1 is that in step (1), MABr is replaced with an equimolar amount of methyl ammonium iodide (MAI), and the concentration of MAI is 5.83 mg / mL.
[0043] Comparative Example 3
[0044] The battery was prepared using the same process as in Example 1, except that MABr was not added in step (1), i.e., the SnO2 electron transport layer was an undoped pure SnO2 layer.
[0045] Comparative Example 4
[0046] The only difference between this comparative example and Example 2 is that in step (1), 10 mg of MABr was added to make the MABr concentration approximately 3.3 mg / mL.
[0047] This concentration is below the lower limit of the preferred range of the present invention, 3 mg / mL, indicating insufficient halogen ions to adequately fill oxygen vacancies.
[0048] Comparative Example 5
[0049] The only difference between this comparative example and Example 2 is that in step (1), 30 mg of MABr is added to make the MABr concentration approximately 10 mg / mL.
[0050] The concentration is close to or slightly higher than the upper limit of the preferred range of the present invention. Excessive concentration can cause aggregation or overdoping, leading to a decrease in performance.
[0051] Comparative Example 6
[0052] The only difference between this comparative example and Example 2 is that in step (1), the sample is annealed in air at 150 °C for 15 min.
[0053] A temperature of 150℃ is too low to completely remove the organic cations of MABr, resulting in carbon residue and a loose film, leading to poor passivation.
[0054] Comparative Example 7
[0055] The only difference between this comparative example and Example 2 is that in step (1), the sample is annealed in air at 180 °C for 15 min.
[0056] The temperature is slightly higher than 150 ℃, but it still cannot completely remove the organic cations of MABr, resulting in carbon residue and a non-dense film, and poor passivation effect.
[0057] Comparative Example 8
[0058] The only difference between this comparative example and Example 2 is that in step (1), the sample is annealed in air at 300 °C for 15 min.
[0059] Excessive temperature causes MABr to decompose and escape, preventing halide ions from being effectively doped and stably attached to the SnO2 surface, and the interface passivation layer disappears.
[0060] Performance test results
[0061] The performance of the AgBiS2 quantum dot thin films and solar cell devices prepared in Examples 1 to 2 and Comparative Examples 1 to 8 was tested.
[0062] Device photovoltaic performance testing: Using a standard AM 1.5G solar simulator (100 mW / cm²) 2 The JV characteristic curves of the solar cells prepared in Examples 1 to 2 and Comparative Examples 1 to 8 were tested.
[0063] Figure 2 This is a comparison of the JV characteristic curves of AgBiS2 quantum dot solar cells obtained by adding MABr, MACl, and MAI to Examples 1 to 3 of the present invention, respectively. It can be seen that compared to the undoped control group, the curve shifts to the right after the introduction of halogen, indicating that the open-circuit voltage (V... OC The fill factor (FF) and fill factor (FF) were significantly improved.
[0064] Figure 3 This is a comparison of the JV characteristic curves of AgBiS2 quantum dot solar cells obtained by adding different concentrations of MABr in Example 2 and Comparative Examples 3 to 5 of the present invention. It can be seen that there is an optimal concentration window for the halogen compound. The optimal V corresponds to the addition of 6 mg / mL of MABr. OCAnd FF. This illustrates that tin oxide doped at different concentrations has a non-monotonic effect of "insufficient passivation at low concentrations and agglomeration at high concentrations".
[0065] Figure 4 This is a comparison of the JV characteristic curves of AgBiS2 quantum dot solar cells obtained at different annealing temperatures in Example 2 and Comparative Examples 6 to 8 of the present invention. It can be seen that when the annealing temperature is too low, the passivation effect is limited due to organic residues and insufficient crystallization; when the annealing temperature is too high, the passivation species are lost due to excessive decomposition.
[0066] Figure 5 The images show a comparison of the UV absorption of SnO2 films obtained with different concentrations of MABr in Example 2 and Comparative Examples 3 to 5 of this invention. It can be seen that, compared with undoped SnO2 films, the absorption intensity in the UV region of the MABr-doped SnO2 films changed, and significant differences were observed in the absorption edge and absorption intensity at a MABr concentration of 6 mg / mL.
[0067] Figure 6 The XRD patterns of the doped SnO2 film obtained by adding MABr in Example 2 of this invention and the pure SnO2 without MABr in Comparative Example 3 are shown. It can be seen that the introduction of trace halogen compounds did not change the bulk lattice structure of SnO2, i.e., no significant change in lattice parameters or formation of new phases occurred. The passivation mechanism mainly occurs in the interstitial spaces, grain boundaries, or surfaces, filling oxygen vacancies and hydroxyl groups, rather than through substitutive bulk doping. This surface / interface modification strategy maintains the excellent intrinsic electron mobility of SnO2 while effectively repairing its surface and interface defects, which is key to improving photoelectric conversion efficiency.
Claims
1. An AgBiS2 quantum dot solar cell, comprising a transparent electrode, an electron transport layer, an absorber layer, a hole transport layer, and a metal electrode, characterized in that, The electron transport layer is a doped tin oxide thin film doped with a halogen compound. The halogen compound and the tin oxide precursor are mixed before film formation to form a uniform doped electron transport layer.
2. The AgBiS2 quantum dot solar cell according to claim 1, characterized in that, The halogen compound is selected from at least one of organic halogen salts, inorganic halogen salts, or halogen ionic liquids.
3. The AgBiS2 quantum dot solar cell according to claim 1, characterized in that, The halogen compound is selected from at least one of methylammonium bromide, methylammonium chloride, methylammonium iodide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, phenylethylammonium bromide, and phenylethylammonium iodide.
4. The AgBiS2 quantum dot solar cell according to claim 1, characterized in that, The thickness of the doped tin oxide film is 5–100 nm.
5. A method for preparing an AgBiS2 quantum dot solar cell according to claim 1, characterized in that, Includes the following steps: (1) The halogen compound is mixed with the tin oxide precursor solution, spin-coated or sprayed onto the surface of the transparent electrode, and then annealed to form a dense tin oxide film doped with the halogen compound. (2) Deposit an AgBiS2 quantum dot absorption layer on the doped tin oxide film; (3) A hole transport layer and a metal electrode are sequentially prepared on the AgBiS2 quantum dot absorption layer to obtain the AgBiS2 quantum dot solar cell.
6. The method for preparing AgBiS2 quantum dot solar cells according to claim 5, characterized in that, In step (1), the annealing temperature is 150-300 °C and the annealing time is 5-60 min.
7. The method for preparing AgBiS2 quantum dot solar cells according to claim 5, characterized in that, In step (1), the concentration of the halogen compound in the tin oxide precursor solution is 1 to 15 mg / mL.
8. The method for preparing AgBiS2 quantum dot solar cells according to claim 5, characterized in that, In step (1), the molar ratio of the halogen compound to the tin oxide precursor is 0.01:1 to 0.5:
1.
9. The method for preparing AgBiS2 quantum dot solar cells according to claim 5, characterized in that, In step (1), the spin coating time is 30 to 60 seconds.
10. The method for preparing AgBiS2 quantum dot solar cells according to claim 5, characterized in that, In step (2), the AgBiS2 quantum dot absorption layer is prepared by a layer-by-layer spin coating combined with a solid-phase ligand exchange process. The solution used for ligand exchange is a 3-mercaptopropionic acid / hexafluoroisopropanol solution with a mass-volume ratio of 0.5-5%.